My bother-in-law called and said his furnace was off again after he was billed $240 by the local repair shop. I called the repair shop but theywouldn't come again until the bill was paid. I said that the bill shouldn't be paid until the furnace works. So I took my tools and meter to town and began trouble shooting. A relay in the fire eye control for the oil burner chattered every time we tried to start the burner. Well, this was easy, I replaced the control. Turned it on and it chattered again. I checked the voltage at the switch, it read 108 volts. I checked the voltage at the panel - 108 volts from A to neutral and 120 volts from B to neutral, and 0 volts from A to B. What the hell, I thought. Something is weird here. The burner breaker was on A bus so I changed it to B bus and the burner took off. I next went to the service. And guess what I found? A fifty year old service panel with two 60 ampere fuses and the one on A phase was open. Apparently, the hot water heater that was on 240 volts was allowing B phase to back feed into the neutral through A phase loads setting up a voltage divider. I asked my brother-in-law if he had any hot water and he said not since the furnace went off. Hey, this is what I should have asked before I spent $80 for a new controller. I asked if some of the lights had been dimming at times. Oh yes, he said. Again, I should have asked that too. But mainly, I should have looked at the service. Who would think a house would have fuses this day and age? As for the service repair shop - well I asked my brother in law if the hot water went off after the repairman was there and he said yes, and that his brother who had been staying in the basement was using some electric heaters to get warm. Darn residential work, it will get you every time.